1. Field of the Invention
This invention relates to novel carboxylated isobutylene/vinylbenzene copolymers and to unique thermoplastic graft copolymers of such carboxylated polymers and pivalolactone. The graft copolymers are useful for the preparation of molded objects and self-supporting flexible films. The carboxylated copolymer substrates are separately useful as general adhesives.
2. Description of the Prior Art
1. N. A. Plate, M. A. Jampolskaya, S. L. Davydova and V. A. Kargin [J. Polymer Sci. (Pt. C), 22, 547 (1969)] discloses the treatment of a metallated copolymer of .alpha.-p-dimethylstyrene and propylene with CO.sub.2 to give a carboxylated copolymer of .alpha.-p-dimethylstyrene and propylene. Metallation and carboxylation of homopolymers of styrene and p-methyl styrene is also disclosed.
2. U.S. Pat. No. 3,168,456 (1965, to Phillips Petroleum Co.) discloses the preparation of polymeric carboxylic acids by exposing a mixture of a 1-olefin (chosen from a group including isobutylene and styrene) and CO.sub.2 to ionizing radiation.
3. U.S. Pat. No. 3,346,631 (1967, to American Synthetic Rubber Corp.) discloses the treatment of copolymers of dienes, e.g., butadiene or isoprene, and an olefin, e.g., styrene or isobutylene, with ozone, followed by a subsequent work-up which leads to carboxylated polymers.
4. Belgian Pat. No. 786,747 describes random graft copolymers containing at least one .beta.-lactone side chain grafted onto an amorphous base polymer through a carbanion, carboxylic anion or alkoxide anion site. The carboxylic anion sites described are those normally present in copolymers derived from esters, amides and anhydrides.